Respirator with speaking diaphragm



March 1956 J. N. MATH'ESON ET AL 2,738,788

RESPIRATOR WITH SPEAKING DIAPHRAGM Filed April 8, 1952 2 Sheets-Sheet l I N VEN TORD JA MES M MA T1155 0N ERIC/I. BETHIG gal March 20, 1956 J N. MATHESON ET AL 2,738,788

RESPIRATOR WITH SPEAKING DIAPHRAGM Filed April 8, 1952 i 2 Sheets-Sheet 2 1 N VEN T 0R5 JAMESNMATHES 01v ERICA. BETHIG ORNfY United States Patent James N. Matheson, West Reading, Pa., assignors to lug, Pa.,

Reading, and Eric A. Bethig, Willson Products, Inc., Read a corporation of Pennsylvania Application April 8, 1952, Serial No. 281,172 Claims. (Cl. 128-146) This invention relates to a respirator and speaking diaphragm assembly which makes it possible to mount a speaking diaphragm on the small surface area provided by a conventional respirator and with an amazing improvement in both clarity and volume of voice transmission as compared to speaking diaphragms of the type conventionally used on gas masks. While the invention is particularly useful for respirators, it is also applicable to gas masks and similar respiratory devices which are worn on the face.

It is known in the art to provide a gas mask with a speaking diaphragm in order to allow the wearer to converse with others while wearing the gas mask. Such speaking diaphragms have had the serious disadvantage of great lack of clarity of transmission as well as a considerable lack in volume of transmission which has necessitated shouting on the part of the wearer in order to be understood. This serious problem has perplexed the art for a considerable length of time. Attempts have been made to improve the clarity and amplification or volume of voice transmission by the provisions of amplifiers, sound boxes and similar devices in association with the speaking diaphragm. Such sound boxes and devices considerably increase space requirements and manufacturing costs and unfortunately contribute only little towards improving the clarity and volume of voice transmission. Furthermore, such assemblies that are at all suitable for satisfactory voice transmission are so cumbersome in construction and large in size as to make them entirely unsuitable for mounting on respirators with. the result that respirators are invariably made without speaking diaphragms since it is felt there is no room for mounting a satisfactory diaphragm.

An object of the present invention is to overcome the above mentioned disadvantages and to provide a novel respirator and speaking diaphragm combination which makes it a practical matter to incorporate a satisfactory speaking diaphragm assembly in a respirator.

A further object of the invention is to provide a novel speaking diaphragm assembly and associated parts which are particularly adaptable and designed for use in a respirator, gas mask or similar face piece.

A more specific object of the present invention is to provide a respirator-speaking diaphragm assembly including a mounting for supporting a plastic speaking diaphragm under tension at all times and in a manner so as to provide an amazing improvement in clarity as well as volume of transmission.

A further object of the invention is to provide a respirator or gas mask with a speaking diaphragm assembly including a mounting for providing automatic tension compensation for the diaphragm to overcome the tendency of its loss of tension as the result of moisture absorption and other causes.

Other objects and advantages of the present invention will become apparent from a study of the following description, taken with the accompanying drawings wherein:

Figure 1 is an elevational view of a respirator including a speaking diaphragm assembly embodying the principles of the present invention;

Figure 2 is an enlarged cross-sectional view taken along line II-II of Figure 1 showing the construction of the speaking diaphragm and associated parts;

Figure 3 is a perspective view of the diaphragm housing shown in Figures 1 and 2;

Figure 4 is a perspective view of the diaphragm with its perimeter crimped into cup-like shape;

Figure 5 is a perspective view of the ring insert for stretching the diaphragm;

Figure 6 is an enlarged, cross-sectional view taken along line VI-VI of Figure 1;

Figure 7 is an enlarged interior view of the exhalation diaphragm and supporting assembly shown in Figure 6;

Figure 8 is a plan view of a modified speaking diaphragm assembly embodying compensating tension control;

Figure 9 is a cross-sectional view taken along line IX-IX of Figure 8;

Figure 10 is a plan view of the ring, and

Figure 11 is a cross-sectional view of the ring shown in Figure 10.

Referring more particularly to Figures 1 and 2 of the drawing, numeral 1 denotes a respirator face piece of rubber or other suitable elastic material and which is substantially cup-shaped with a pear-shaped outline so that its inturned marginal edge will provide a cushioned, air-tight fit around the nose, cheeks and chin of the wearer. Numeral 2 denotes an exhalation valve of any well known construction such as a thin, flexible rubber diaphragm which is centrally mounted and which normally covers an apertured portion of face piece 1. On the cheek or lobe portions of face piece 1 are mounted a pair of filter box bases 3, including threaded portions onto which are screw threadedly mounted perforated lids or caps 4 having a plurality of perforations 5. Filter discs or pads 6 may be sandwiched between the outer perimetrical portions of covers 4 and bases 3 so as to provide a dust-tight seal. Of course, other types of filter pads, such as hollow pads with an annular filter disc portion attached, may be used instead.

An important feature of the present invention resides in the placement and construction of the speaking dia phragm assembly for the purpose of transmitting voice signals with great fidelity and considerably greater amplification than speaking diaphragms of conventional construction. The speaking diaphragm assembly, which is generally denoted by numeral 7 and is shown more clearly in Figure 2, is protected by a perforated plate 8 of disc shape which is rigidly mounted on an annular diaphragm housing 9 by merely turning in an integral outstanding flange 10 over the rim of the perforated plate 8. Diaphragm housing or ring 9 has a perimetrical well portion which is detachably fitted to a hole portion of slightly less diameter of face piece 1 so that the housing may be quickly and easily attached to or detached from the face piece in a yieldable manner for replacement of the diaphragm.

An important feature of the invention resides in the choice and form of the diaphragm material as well as the manner in which it is assembled in relationship with adjoining parts. While generally speaking, plastic materials have been found to be suitable diaphragm materials, those which have been commonly used are not suitable for the purposes of the present invention. For instance, cellophane tears too easily. It has not been heretofore appreciated that certain additional features are necessary which control the selection of the particular plastic material as well as its mode of assembly. We

diaphragm securing have found cellulose acetate to be fairly good plastic material for use as a speaking diaphragm provided it is placed under tension in single sheet form. Heretofore, plastic materials used have usually been mounted in the form of a plurality of plies or separate layers in an untensioned condition in the mounted position. This results in very unsatisfactory transmission of speech, not only from the standpoint of lack of fidelity, resulting in difiiculty of understanding of voice signals or speech, but lack of suflicient volume of transmission, which necessitates shouting on the part of the wearer in order to be understood.

We have found that by making the plastic sheet of single ply construction, and by maintaining its thickness within a critical dimension of between about one thousandths and two thousandths inch, and additionally, by maintaining the plastic sheet or diaphragm under tension at all times, an amazing improvement in voice transmission is obtained, both in fidelity of transmission and volume. We further found that while cellulose acetate, for example, is a fairly good material when mounted in the manner indicated, it has the disadvantage of inherently expanding after prolonged contact with moisture resulting from exhalation condensate caused by the wearer. This expansion tends to loosen the diaphragm and greatly reduce its tension to such an ex tent as to create an annoying resonating vibration when the wearer converses.

After considerable experimentation, we found that polyethylene is superior to cellulose acetate and to other diaphragm materials since it not only has excellent voice transmitting characteristics, but it is impervious to moisture condensate formed and is more puncture resistant than other plastic materials. Also, it is easier to assemble and does not buckle nearly as much When insorted in the diaphragm housing. Also, it is strong and can be substantially stretched without breaking. When it is of proper thickness, it has excellent voice transmitting characteristics. This thickness is critical and is between about .001 and .002 inch, preferably about .002 inch. In short, it has ideal characteristics for a speaking diaphragm which is mounted in the manner to be described and which is subjected to moisture from exhalation of the wearer without deleterious elfects from the standpoint of voice transmission.

As pointed out hereinbefore, it is not only important to select a plastic material having optimum voice transmitting characteristics, but such material must be mounted in a very special way in order to obtain the full benefits of the present invention.

Figure 2 more clearly shows a mounting embodying the principles of the present invention for mounting the diaphragm in tensioned condition and in a manner so that its peripheral edge is free from contact with adjoining surfaces. A thin, disc-shaped piece of polyethylene constituting diaphragm 11 is placed on the right-hand surface of housing 9 as viewed in Figure 2 having a diameter substantially equal to the outer diameter of the housing 9. Thereafter, a ring or annular insert 12 of brass or other suitable material is forced into the annular space of housing 9, thereby crimpingthe rim portion of diaphragm 11 into substantially cup shape as shown in Figures 2 and 4. Substantially improved voice transmission is obtained when the inwardly projecting perimeter of ring 12 is not fiat and is, instead, of pointed construction, with a slightly rounded diaphragm-engaging portion, so that an abrupt or pointed parting line is provided on the perimeter of the tensioned disc portion of the diaphragm. Another important consideration in mounting the diaphragm is to prevent contact between the rim portion of the tensioned diaphragm and any adjoining part, such as the radially inwardly extending flange of housing 9. A small gap is preferably provided between such flange and the rim portion of the tensioned diaphragm so as to prevent contact which otherwise would result in annoying, resonating vibration and insufficient amplitude of the transmitted voice signals. To insure this gap and to prevent over-tensioning and breaking of the plastic diaphragm material when its marginal portion is being turned and folded in, a shoulder portion 120 is provided which serves as a limit stop for limiting the movement of the innermost edge portion of ring 12.

The gap between ring insert 12 and the diaphragm housing 9 should be of the order of between about one to twice the thickness of the diaphragm. Therefore, for a diaphragm thickness of 0.002 inch, the gap may be between .002 and .004 inch, and preferably about .003 inch so as to allow for the additional thickness provided by the folds 11a as shown in Figure 4. An air-tight seal is thereby provided. The outer diameter of housing 9 may be of the order of 1 /4 inch. However, this size is not critical.

As pointed out above, it was unexpectedly found that amazingly improved results are obtained in both clarity and volume of transmission if the portion of ring 12 which is closest to the outer perimeter of the diaphragm 11 at the point where the diaphragm is bent inwardly and tensioned is made substantially pointed instead of flat. A fiat edge as commonly used does not allow free vibration of the tensioned portion of the diaphragm, and introduces an annoying resonating vibration. The edge 1211 should not, however, be a knife edge, since this would tend to cut the diaphragm, but it should be a substantially pointed edge, for example, one having a flat plateau of only about .02 inch at the diaphragm contacting portion and it should preferably have a small outer radius of curvature of about .008 inch at the portion of greatest diameter of portion 12b. Likewise, the corner 91) of the housing should also have a small diameter curvature of about .008 inch to form a break edge that will not sever the diaphragm material.

As ring 12 is pushed into place within housing 9, it will tend to stretch diaphragm 11 very taut and the stretching action will be stopped when shoulder 1211 comes into contact with housing 9. An air-tight seal will be provided by the portion of the diaphragm material which is sandwiched between insert 12 and housing 9, particularly the folds 11:: which are formed under compression.

When it is desired to remove the diaphragm for replacement, by merely grasping the wire-shaped handle 13 and pulling ring insert 12 outwardly, the diaphragm is made free and can be readily replaced.

Another amazing discovery we made was that the presence of a conventional type inhalation valve introduces an extremely annoying resonating vibration which garbles the voice signals and makes them not clearly understood. The conventional type of inhalation valve is in the form of a very flexible, thin disc which is supported centrally, only, in confronting relationship with a perforated portion of the face piece. We found that by providing a two-point support for the inhalation diaphragm, to avoid the freedom of movement in a circumferential direction, that considerable improvement was obtained in the clarity of voice transmission.

Figures 6 and 7 show the specific mounting of the inhalation valve or diaphragm 19 which is in the form of a very thin, substantially diamond-shaped piece having apertures near the outermost edges of the major dimension which are fitted into rubber stubs 18 integrally formed on the interior of face piece 1 and exending therefrom at an angle of about On the base 3 of the filter box, there is mounted a grommet 16 which is turned in so as to clamp the inhalation outlet hole provided in face piece 1 at both sides of the face piece lobes. That is, there are two inhalation valve assemblies .such as shown in Figures 6 and 7, one within the base of each filter box. When airis breathed inwardly, the diaphragm 19 will flex away from seating contact with grommets 16 to allow air to be drawn into the face piece. When air is exhaled, through exhalation valve 2, diaphragm 19 will be pushed into tight air-sealing engagement with grommets 16 to prevent escape of air therethrough. By the provision of two points of support and the slight tensioning provided in diaphragm 19 as the result of its mounting on stubs 18, there is no freedom of vibration in a circumferential direction, therefore greater clarity of transmission will be attained.

Figures 8 to 11, inclusive, show a modification of the diaphragm assembly in which there is embodied automatic tension compensation for the diaphragm to overcome the tendency of loss of tension as the result of moisture absorption caused by exhalation of the wearer and other causes. A diaphragm housing 22 of brass or other suitable material is provided having a retaining lip 22a which is shown in the form before the lip is turned over onto the rim of the perforated plate 8 such as shown in Figure 2. An integral threaded section 21 is provided for receiving acorrespondingly threaded insert 27 such as shown in Figures and 11, which insert is provided with a diametrical rib 27a which may be grasped so as to facilitate screwing of the insert onto housing 22. A compensating low durometer rubber gasket 23 is provided within housing 22 which coacts with a high durometer rubber gasket 24 which is employed for seating the diaphragm 28 and for insuring a gas-tight seal. A metal ring 25 in the form of an insert is provided for mounting the diaphragm, which ring has a narrow edge for contacting the diaphragm in the manner of edge 12b shown in Figure 2 and for the purpose of improving the clarity of transmission. This edge may also have a plateau of about .02 inch. The screw threaded insert 27 when in place will secure the diaphragm in housing 22 against gasket 24. It Will be apparent that inasmuch as the elasticity of gasket 23 is greater than that of gasket 24, gasket 23 will exert continuous compensating pressure against insert 25, tending to push it outwardly of housing 22, thereby automatically tensioning the diaphragm 28 under varying conditions of moisture which would otherwise tend to cause a loss of tension of the diaphragm. Rubber gasket 24 also aids in tensioniug the diaphragm and a permanent adjustment of the tension provided thereby is determined by the tightness of screwing of ring 27 which compresses gasket 24.

It will be apparent that other equivalent means may be provided for yieldingly mounting ring 25 so as to exert constant tension on the diaphragm and automatically compensate for decreases of tension thereof caused by moisture or other conditions. Maintenance of the diaphragm under tension is an important condition in order to obtain optimum results in both clarity and volume of voice transmission.

While polyethylene has been found to be the ideal plastic material, particularly within a range of thickness between .001 and .002 inch (particularly in the neighborhood of .002 inch), it will be apparent that possibly other plastic materials having about the same strength and the same modulus of elasticity may also be provided so long as they are in the form of a single ply sheet maintained under tension.

While the speaking diaphragm disclosed hereinabove has been described as being useful in a respirator, it should be noted that it is equally suitable for use in a gas mask or similar respiratory device so long as it is placed as closely as possible in front of the mouth of the wearer for the best results.

Thus it will be seen that we have provided an efficient speaking diaphragm assembly which is particularly adapted for use in a respirator or gas mask and which for the first time enables the use of a speaking diaphragm in the small area of the face piece of a conventional respirator, thereby allowing the wearer of a respirator to talk freely and to be understood by others; furthermore, we have provided a novel speaking diaphragm assembly for respirators and similar devices which provides an amazing and startling increase in both clarity and volume of voice transmission; furthermore, We have provided a speaking diaphragm assembly which can be readily attached to or detached from a respirator or similar device and which includes a diaphragm which is easily and quickly detached and replaced, which assembly is made up of simple and inexpensive parts which are inex pensive-1y manufactured.

While we have illustrated and described several embodiments of our invention, it will be understood that these are by way of illustration only, and that various changes and modifications may be made within the con templation of our invention and within the scope of the following claims.

We claim:

1. In a respiratory device having a face piece adapted to fit, on the face of the wearer, in combination, a speaking diaphragm assembly mounted on the portion of the face piece adapted to confront the mouth of the wearer, said diaphragm assembly including a mounting ring detachably secured to an opening of said face piece in said portion, and a single sheet polyethylene diaphragm mounted under tension within said ring and having a thickness of the order of .002 inch.

2. In a breathing apparatus including a face piece having an opening adapted to confront the mouth of the wearer, a ring having a well portion of channel shape cross section about its rim portion to form a seat for and detachable, air-tight fit with said face piece opening, an annular insert adapted to be slip fitted within said ring, a single sheet of voice transmitting inelastic plastic ma terial mounted on one face of said insert with its rim portion folded and tightly sandwiched between said insert and ring and with its central portion tightly stretched and under tension.

3. Apparatus recited in claim 2 wherein said plastic material consists of polyethylene and is of a thickness of the order of .002 inch.

4. In a breathing apparatus including a face piece having an opening adapted to confront the mouth of the wearer, a ring having a well portion about its rim portion to form a detachable, air-tight fit with said face piece opening, an annular insert adapted to be fitted within said ring, a sheet of plastic material mounted on one face of said insert with its rim portion folded and tightly sandwiched between said insert and ring and with its central portion tightly stretched and under tension as the result of insertion of said insert within said ring, a perforated plate supported on one face of said ring for protecting said diaphragm, said annular insert having a tapered edge portion for contacting the rim portion of the stretched diaphragm, said annular insert having a shoulder portion extending radially outwardly on the face opposite the face on which the diaphragm is stretched for limiting inward movement of said tapered portion and for spacing the rim portion of the stretched diaphragm from the remainder of said ring.

5. Apparatus as recited in claim 4 wherein said tapered portion of the ring terminates in an annular plateau having a thickness or" the order of .02 inch and having a curved outer rim portion which engages the diaphragm, and a handle secured to said insert for facilitating removal thereof from said ring.

6. In a respirator having a face piece adapted to fit over the nose, cheeks and chin of the wearer, in combination, a speaking diaphragm assembly mounted on the portion of the face piece adapted to confront the mouth of the wearer, said diaphragm assembly including a detachable mounting ring and a single sheet plastic diaphragm mounted under tension within said ring and having a thickness of the order of .002 inch, said respirator also including inhalation and exhalation valves, said inhalation valve comprising a substantially diamondshaped thin, flexible diaphragm supported at the opposite edges of its major dimension, and an inhalation port including a grommet on which said inhalation valve is adapted to become seated upon exhalation of the wearer and unseated upon inhalation, and a pair of stubs integrally secured to said face piece and extending at an angle of 45 from the surface of the portion of the respirator from which they emerge and 90 from each other for supporting said diaphragm under tension at the opposite edges along the major dimension.

7. In a respirator having a face piece adapted to fit over the nose, cheeks and chin of the wearer, in combination, a speaking diaphragm assembly mounted on a portion of the face piece adapted to confront the mouth of the wearer, a pair of filter boxes having base portions supported on the cheek surrounding portions of said face piece, said base portions including inhalation valves comprising thin, rubber diaphragms of substantially diamond shape and which are supported at the corners at the extremities of the major dimension, said speaking diaphragm assembly comprising a readily detachable supporting frame element having mounted therein a tightly stretched sheet of plastic material of the order of .002 inch thick.

8. A respirator as recited in claim 7 wherein said plastic material consists of polyethylene.

9. In a respirator having a face piece adapted to fit over the nose, cheeks and chin of the wearer, in combination, a speaking diaphragm assembly mounted on the portion of the face piece adapted to confront the mouth of the wearer, said diaphragm assembly including a detachable mounting ring and a single sheet polyethylene diaphragm mounted under tension within said ring and having a thickness of the order of .002 inch, an annular insert across one face of which said diaphragm is stretched and which insert is slidably fitted within said ring, and means including a gasket of elastic material for exerting continual pressure at all times on said annular fit insert so as to compensate for any lessening of tension as the result of moisture absorption or other causes.

10. In a breathing apparatus, including a face piece having an opening adapted to confront the mouth of the wearer, a ring having a well portion about its rim to form a detachably air-tight fit with said face piece opening, an annular insert adapted to be fitted within said ring, a low durometer rubber gasket interposed between said insert and a radially inwardly extension flange of said ring, a high durometer rubber gasket interposed between said ring and an inwardly threaded portion of the ring adjacent the opposite face of said insert, and a screw threaded diaphragm securing ring 'threadedly engaged to said threaded portion and adapted to cause said high durometer gasket to seat against an outer peripheral portion of said insert when covered with a thin single sheet of voice transmitting material draped over said Last mentioned portion of said insert and constantly maintained under tension as the result of the resilience of said low and high durometer gaskets.

References Cited in the file of this patent UNITED STATES PATENTS 1,204,420 Edison Nov. 14, 1916 1,446,911 Lescarboura Feb. 27, 1923 1,701,277 Shindel Feb. 5, 1929 1,762,695 Monro June 10, 1930 2,019,928 Punton Nov. 5, 1935 2,326,650 Husted Aug. 10, 1943 2,410,454 Motsinger Nov. 5, 1946 2,705,052 Workinger Mar. 29, 1955 FOREIGN PATENTS 572,888 Great Britain Oct. 29, 1945 660,419 Great Britain Nov. 7, 1951 OTHER REFERENCES Modern Plastics, vol. 25, No. 6, Feb. 1948, pp. 77-78. 

